This study is a multicenter prospective randomized controlled clinical trial that will evaluate emergency department use of Tc99m-sestamibi scanning as an aid in emergency department triage of patients with symptoms suggestive of acute cardiac ischemia (ACI) who have normal or non-diagnostic EKG's. This study will determine the impact of sestamibi scanning on the accuracy of emergency department triage decisions: the degree to which those with (ACI) are hospitalized and those without (ACI) are discharged. A secondary aim of study will be to evaluate the impact of sestamibi scanning on hospital costs.